JP4535098B2 - Manufacturing method of multilayer ceramic electronic component - Google Patents

Description

  The present invention relates to a method for manufacturing a multilayer ceramic electronic component, and more particularly to a method for forming a conductor wiring layer provided in a multilayer ceramic electronic component.

  As a multilayer ceramic electronic component which is of interest to the present invention, there is a multilayer ceramic substrate. In recent years, there has been an increasing demand for miniaturization in order to enable high-speed propagation of multilayer ceramic substrates on which semiconductor elements such as ICs and LSIs with higher frequency and higher density are mounted.

Therefore, the ceramic layer provided in the multilayer ceramic substrate is required to be composed of a material having a lower dielectric constant. On the other hand, in the case of a wiring conductor such as a conductor wiring layer or a via-hole conductor provided in the multilayer ceramic substrate, It is required to be made of a material having a lower electric resistance. Low-temperature sintered ceramics that can be sintered at a temperature of 1000 ° C. or less, such as BaO—Al ₂ O ₃ —SiO ₂ mixed ceramics, for example, have attracted attention as a material constituting a ceramic layer that gives a lower dielectric constant. On the other hand, as a material constituting the wiring conductor, a metal that can be fired simultaneously with a low-temperature sintered ceramic and has a relatively low electric resistance, for example, copper, silver, gold, aluminum, nickel, or the like, has attracted attention. .

  As described above, a multilayer ceramic substrate including a ceramic layer composed of a low-temperature sintered ceramic is generally manufactured as follows.

  First, a slurry obtained by mixing a low-temperature sintered ceramic raw material powder, an organic binder, and an organic solvent is formed into a sheet by a sheet forming method such as a doctor blade method to produce a ceramic green sheet. Next, the ceramic green sheet is punched with a through hole for a via-hole conductor, and the through hole is filled with a conductive paste containing a copper metallized composition or a silver metallized composition, and on the ceramic green sheet, A conductive wiring layer is formed by a screen printing method or the like using the same conductive paste. Next, a heating process for removing the binder is performed on the raw laminate obtained by laminating a plurality of ceramic green sheets and pressing in the laminating direction, and then a firing process.

  However, according to the method for manufacturing a multilayer ceramic substrate as described above, since the wiring conductor such as the conductor wiring layer and the via-hole conductor is composed of a sintered body of a conductive paste, In addition, the presence of grain boundaries is inevitable, and there is a limit to reducing the resistance of the wiring conductor, which is not necessarily suitable for forming a high-frequency circuit that requires further reduction in resistance.

  In addition, there is a limit to increasing the printing accuracy of the conductive paste for forming the conductor wiring layer. Therefore, for example, it is difficult to form fine wiring narrower than a wiring width of 100 μm with a good yield. Therefore, there is a limit to satisfy the demand for further downsizing of the multilayer ceramic substrate and higher density of wiring.

  Therefore, a multilayer ceramic substrate using a metal foil made of copper or the like as a conductor wiring layer has been proposed. By configuring the conductor wiring layer from a metal foil, the metal foil is dense, so the resistance of the conductor wiring layer can be reduced, and fine patterning is possible by using a photolithography technique. Can be expected.

  However, when a metal foil is used for forming the conductor wiring layer, the following problems that are difficult to encounter when using a conductive paste are caused.

  That is, since the metal foil generally has poor reactivity with the ceramic layer, the adhesive strength to the ceramic layer is low. In particular, the finer the conductor wiring layer provided by the metal foil, the lower the adhesive strength, and the more the conductor wiring layer made of the metal foil is easily peeled off from the ceramic layer.

  Further, the metal foil hardly undergoes thermal shrinkage in the firing process. Therefore, it is difficult to match the shrinkage behavior on the ceramic layer side and the shrinkage behavior of the metal foil in the firing process, which causes problems such as delamination or cracks in a laminate composed of multiple ceramic layers. There is.

  Moreover, in order to suppress the shrinkage in the main surface direction of the ceramic layer in the firing process, even when a so-called no-shrink process is applied, when the binder removal process is performed, the metal foil is heated in an oxidizing atmosphere. In the laminate, delamination and cracks occur due to volume expansion due to oxidation and stress due to the difference in thermal expansion coefficient between the ceramic layer and the metal foil in the cooling process after the firing process. It is not possible to completely solve the problem that is likely to occur.

  When a conductive paste is used to form the conductive wiring layer, the conductive wiring layer has a sintered structure of metal particles, so there are many voids in the conductive wiring layer, and contact between the metal particles. In addition to being able to change the state, filler components such as ceramic and glass can be added to the conductive paste. It is relatively easy to adjust between.

  In relation to the problems encountered when using the metal foil described above, for example, in JP-A-7-86743 (Patent Document 1), Cu foil used for forming a conductor wiring layer provided in a multilayer ceramic substrate is used. It is described that a CuO foil is formed by oxidation treatment in a state of being stuck on a polymer film, and a raw laminate is produced using this CuO foil. According to this method, volume expansion due to oxidation of the Cu foil can be suppressed in the binder removal step in the air atmosphere, and CuO is reduced to Cu in the subsequent firing step in the reducing atmosphere, This can be a conductor.

  However, in the method described in Patent Document 1 described above, the oxidation treatment of the Cu foil is performed in a state where the Cu foil is pasted on the polymer film. Therefore, when Cu is oxidized to CuO, about 77 % Volume expansion occurs, the CuO foil on the polymer film may be greatly deformed and peeled off from the polymer film. Although the peeling of the CuO foil from the ceramic layer during the binder removal process can be suppressed, when CuO is reduced to Cu in a reducing atmosphere, a volume reduction of about 44% occurs. You may encounter the problem of frequent delamination in the body.

  Japanese Patent Laid-Open No. 2001-15930 (Patent Document 2) discloses a thermal expansion coefficient between a substrate and a wiring circuit layer after firing while using a high-purity metal conductor made of a metal foil for the wiring circuit layer of a glass ceramic substrate. It is described that an attempt is made to suppress peeling of the wiring circuit layer in the cooling process after firing so that the difference between the two is 25 ppm to 800 ° C. or less.

  However, the technique described in Patent Document 2 described above is for suppressing the peeling of the wiring circuit layer after firing, and suppresses the peeling of the wiring circuit layer during firing, particularly during ceramic sintering. Not trying. Therefore, when the ceramic is sintered, the reactivity between the metal foil and the ceramic is poor, and the adhesion between each other cannot be ensured. Therefore, depending on the composition of the glass ceramic substrate, the wiring circuit layer made of the metal foil may be formed during firing. The problem of peeling off from the glass ceramic substrate may be encountered.

  The problems as described above are not limited to a multilayer ceramic substrate, but include a multilayer ceramic body including a multilayer body including a plurality of laminated ceramic layers, and a conductor wiring layer made of a metal foil formed on the ceramic layer. As long as it is an electronic component, it can be applied to any multilayer ceramic electronic component.

The same problem is encountered when the metal foil constituting the above-described conductor wiring layer is replaced with a metal wire.
JP 7-86743 A JP 2001-15930 A

  Therefore, an object of the present invention is to provide a method for manufacturing a multilayer ceramic electronic component that can solve the above-described problems.

The present invention includes a laminate composed of a plurality of laminated ceramic layers, and a conductor wiring layer formed on the ceramic layer. The ceramic layer is made of a low-temperature sintered ceramic material in which glass is produced during firing. The laminate includes an inorganic material powder for shrinkage suppression that is positioned along a specific interface between the laminated ceramic layers and that does not sinter at the sintering temperature of the low-temperature sintered ceramic material contained in the ceramic layer. The present invention is directed to a method of manufacturing a multilayer ceramic electronic component that further includes a constraining layer, and is characterized by having the following configuration in order to solve the technical problem described above.

That is, in the method for manufacturing a multilayer ceramic electronic component according to the present invention, the step of preparing a metal foil or metal wire containing Cu, which becomes the conductor wiring layer, and at least one surface of the surface of the metal foil or metal wire, A step of covering with Cu ₂ O, a step of holding the conductor wiring layer with a ceramic green sheet to be a ceramic layer, a step of stacking a plurality of ceramic green sheets holding the conductor wiring layer, and a plurality of stacked ceramics Rutotomoni the step of firing the laminate of the raw formed with a green sheet is performed, the conductor wiring layer, the step of holding the ceramic green sheets to serve as the ceramic layer, the foregoing on a specific ceramic green sheets forming an interlayer constraining layer, the above one side covered by Cu ₂ O A step of holding the conductor wiring layer by the ceramic green sheet formed with the interlayer constraining layer so as to be in contact with the interlayer constraining layer, and a step of laminating the plurality of ceramic green sheets holding the conductor wiring layer, The step of laminating a plurality of ceramic green sheets is performed such that the interlayer constraining layer is positioned along the interface between the plurality of ceramic green sheets .

In the present invention, it is preferable that the step of covering the metal foil or metal wire with Cu ₂ O includes a step of heat-treating at least a part of the surface of the metal foil or metal wire in an oxidizing atmosphere.

As described above, according to the present invention, since the conductor wiring layer composed of the metal foil or the metal wire is covered with Cu ₂ O, these surface coatings form an anchor structure with respect to the ceramic green sheet in the firing step. As a result, the adhesive force between the conductor wiring layer and the ceramic green sheet is improved, so that the problem that the conductor wiring layer easily peels off from the ceramic layer in the laminated body after sintering can be avoided.

In addition, according to the present invention, an interlayer constrained layer is formed , and the volume constriction associated with the sintering of the ceramic can be suppressed by the interlayer constrained layer, so that the contraction behavior of the interface between the conductor wiring layer and the ceramic layer is reduced. Since the stress resulting from the difference is suppressed, the above-described effect can be made more perfect.

  In the following, in describing embodiments of the present invention, a multilayer ceramic substrate as an example of a multilayer ceramic electronic component will be described.

  FIG. 1 is a cross-sectional view schematically showing a multilayer ceramic substrate 1 obtained by applying one embodiment of the present invention.

  The multilayer ceramic substrate 1 includes a laminated body 3 including a plurality of laminated ceramic layers 2 and several conductor wiring layers 4 formed on the ceramic layer 2. In this embodiment, several via-hole conductors 5 are further provided so as to penetrate a specific ceramic layer 2 in the thickness direction while being connected to a specific one of the conductor wiring layers 4.

  Moreover, in this embodiment, the interlayer constrained layer 6 including the inorganic material powder for shrinkage suppression that does not sinter at the sintering temperature of the ceramic material powder for obtaining the ceramic constituting the ceramic layer 2 is provided at the interface between the ceramic layers 2. Is located along. In FIG. 1, the interlayer constraining layer 6 is located along all of the interfaces between the ceramic layers 2, but may be located only along specific interfaces.

  A chip-shaped electronic component 7 such as a semiconductor IC chip is mounted on the multilayer body 3 provided in the multilayer ceramic substrate 1. The chip-shaped electronic component 7 is electrically connected and mechanically fixed to the conductor wiring layer 4 formed on the outer surface of the multilayer body 3 on the upper surface side through, for example, solder bumps 8. The The conductor wiring layer 4 formed on the lower surface side of the multilayer body 3 is used when the multilayer ceramic substrate 1 is mounted on a mother board (not shown).

In such a multilayer ceramic substrate 1, the conductor wiring layer 4 is made of a metal foil containing Cu, and at least a part of the surface thereof is covered with Cu ₂ O.

  In order to manufacture the multilayer ceramic substrate 1 described above, each process as described with reference to FIGS. 2 to 4 is performed.

First, as shown in FIG. 2A, a metal foil 11 containing Cu, which will be the conductor wiring layer 4, is prepared. As the metal foil 11 made of Cu, it is preferable to use one having an electric conductivity of 1.0 × 10 ⁵ Ω ⁻¹ · cm ⁻¹ or more.

Next, one side or both sides of the metal foil 11 containing Cu are covered with Cu ₂ O. In order to make the surface of the metal foil 11 containing Cu covered with Cu ₂ O, for example, the metal foil 11 containing Cu is heat-treated at a temperature of 500 ° C. or less in an oxidizing atmosphere. As an example, when the metal foil 11 has a thickness of 18 μm and is made of Cu, the metal foil 11 is about 15 to 60 minutes using an oven set at a temperature of 400 ° C. in an air atmosphere. by heat treatment, the metal foil 11 can be internal to the state is and the surface of Cu covered with Cu ₂ O.

In addition, when heat-treating the metal foil 11 made of Cu, if a heat treatment temperature higher than 500 ° C. or a heat treatment time exceeding 60 minutes is applied, the surface of the metal foil 11 is CuO while Cu is inside. Therefore, the difference in volume expansion between the inside and the surface of the metal foil 11 becomes too large, cracks occur in the metal foil 11, and it is impossible to perform fine etching in a later process. May be. Therefore, in the case of the metal foil 11 containing Cu, it is necessary to form Cu ₂ O having a smaller volume expansion on the surface.

In order to obtain a state in which the surface of the metal foil 11 containing Cu is covered with Cu ₂ O, the surface of the metal foil 11 is treated with, for example, hydrochloric acid of 6N or less instead of the above-described method, and then about 25 ° C. You may make it leave in the air of the temperature of.

In order to further improve the transferability or adhesion of the metal foil 11 to a ceramic green sheet to be described later, one or both surfaces of the metal foil 11 may be roughened to such an extent that high frequency characteristics do not become a problem. The step for roughening the surface is preferably performed before the step of covering the surface of the metal foil 11 with Cu ₂ O as described above. Moreover, the process of roughening the surface of the metal foil 11 is performed, for example, using a known plating method so that a specific metal such as Cu is thinly deposited on the surface of the metal foil 11.

  Next, as shown in FIG. 2 (2), the metal foil 11 is stuck on the support 12. As the support 12, for example, an organic film, a glass plate, an alumina plate, or the like is used. In addition, an adhesive or the like is applied to attach the metal foil 11 on the support 12.

  Next, by etching the metal foil 11 using a photolithography technique, the metal foil 11 is patterned as shown in FIG. 2 (3), and the conductor wiring layer shown in FIG. A shape for 4 is given.

  More specifically, after a photosensitive film is attached to the surface of the metal foil 11 shown in FIG. 2 (2), this is masked with a glass original plate on which a desired exposure pattern is formed, and an exposure process is performed. Development processing is performed so as to give a desired pattern to the photosensitive film. Next, using the photosensitive film patterned as described above as a resist, the metal foil 11 is etched to give the metal foil 11 a shape for the conductor wiring layer 4. In etching the metal foil 11, for example, a solution of ammonium peroxodisulfate or ferric chloride is used as an etchant.

  In order to give the metal foil 11 a shape for the conductor wiring layer 4, in addition to the photolithography technique described above, for example, a plating method using a mask, a laser processing method, a punching method using a punch or the like is applied. You can also.

If only one side of the metal foil 11 should be covered with Cu ₂ O or if the surface should be roughened, the stage shown in FIG. 2 (2) or FIG. 2 (3) In the stage shown in (1), these covering step and roughening step may be performed. For example, in the stage shown in FIG. 2 (3), the metal foil 11 made of Cu is immersed in hydrochloric acid together with the support 12 and then placed in an oven set at a temperature of 100 ° C. or lower for 30 minutes. Cu ₂ O can be formed on the surface of the metal foil 11.

  On the other hand, as shown in FIG. 3A, a ceramic green sheet 21 to be the ceramic layer 2 is prepared. The ceramic green sheet 21 can be sintered at a temperature of 1000 ° C. or less, for example, in order to enable simultaneous firing with the conductor wiring layer 4 composed of the metal foil 11 containing Cu in a firing step described later. It is preferable that it contains a low-temperature sintered ceramic material.

  The ceramic green sheet 21 is, for example, a mixture of barium oxide, silicon oxide, alumina, calcium oxide and boron oxide powder, a binder made of polyvinyl butyral, a plasticizer made of di-n-butyl phthalate, toluene and A slurry obtained by mixing a solvent composed of propylene alcohol can be obtained by forming a slurry on an organic film by a doctor blade method or the like and drying it.

  As the low-temperature sintered ceramic material contained in the ceramic green sheet 21, in addition to those in which glass is generated during firing as in the above example, a sintering aid such as glass, copper oxide, or magnesium oxide is previously contained. It is possible to use a composition that can be sintered at a lower temperature. Moreover, you may use things other than said example also about the binder, the plasticizer, and solvent which are contained in the ceramic green sheet 21. FIG.

  Next, as shown in FIG. 3 (2), the interlayer constrained layer 6 includes an inorganic material powder for shrinkage suppression not sintered at the sintering temperature of the ceramic material powder contained in the ceramic green sheet 21 on the ceramic green sheet 21. Is formed. This interlayer constrained layer 6 is also shown in FIG.

  As described above, when the ceramic material powder contained in the ceramic green sheet 21 can be sintered at a temperature of 1000 ° C. or lower, the interlayer constrained layer 6 is made of, for example, alumina, mullite, aluminum nitride, glass ceramic, zirconia, anodic A binder comprising 15 to 60% by volume of a borosilicate glass powder having a softening point of 780 ° C. and a particle size of 1.5 μm, and comprising polyvinyl butyral, the main component being at least one of each of site, forsterite and cordierite powders; A slurry obtained by mixing a plasticizer composed of di-n-butyl phthalate and a solvent composed of toluene and isopropylene alcohol is applied onto the ceramic green sheet 21 and dried.

  As described above, when the content of the glass powder contained in the interlayer constrained layer 6 is less than 15% by volume, the glass provided by the glass powder is an inorganic material for suppressing shrinkage such as alumina in the firing step described later. Since it does not sufficiently penetrate into the gaps between the powders, not only does it not sufficiently work as an adhesive layer, but also the shrinkage-inhibiting inorganic material powder cannot be sufficiently solidified, resulting in voids, and the conductive wiring layer 4 and the interlayer constraining layer 6 The adhesion area at the interface decreases, and therefore the adhesion force becomes extremely weak, making it impossible to put the laminate 3 shown in FIG. 1 into practical use.

  On the other hand, when the content of the glass powder is more than 60% by volume, the liquid phase glass is interposed between the inorganic material powder for shrinkage suppression such as alumina in the baking process described later, and the interlayer constraint The effect of suppressing the shrinkage of the ceramic green sheet 21 by the layer 6 does not work sufficiently, and the resulting laminate 3 is deformed or cracked due to the difference in thermal stress between the conductor wiring layer 4 and the ceramic green sheet 21, and the laminate 3 Cannot be put to practical use.

  From these things, in order not to produce a deformation | transformation, a crack, etc. of the obtained laminated body 3, ensuring the favorable adhesive force by glass powder, the addition amount of glass powder is 15-60 volume%. It is preferably 25 to 45% by volume.

In addition, the glass added to the interlayer constrained layer 6 has a viscosity of 10 ^6.7 Pa · s ⁻¹ or less below the firing temperature, filling gaps in the inorganic material powder for shrinkage suppression such as alumina, and the like. As such glass, for example, amorphous glass having a high softening point, crystallized glass whose viscosity increases after being densified, and oxide in which a liquid phase is generated at the end of firing A mixture or the like can be used. Further, this glass serves as a solidification aid for the inorganic material powder for suppressing shrinkage contained in the interlayer constrained layer 6 in the temperature range of 850 to 950 ° C. in which the ceramic green sheet 21 is shrunk in the firing step. In addition, it is preferable that the viscosity does not decrease so much that it flows out of the interlayer constrained layer 6. However, when glass or an oxide that does not generate a liquid phase is added in the firing step, it cannot be densified without filling the gaps in the inorganic material powder for shrinkage suppression contained in the interlayer constrained layer 6, The constraining layer 6 cannot be solidified.

  As shown in FIG. 3B, a known printing method or doctor blade method can be applied as a slurry coating method for forming the interlayer constrained layer 6 on the ceramic green sheet 21. In this case, the slurry may be applied only to the region corresponding to the region where the conductor wiring layer 4 is formed, or in order not to consider the alignment accuracy, You may make it apply | coat over the whole surface.

  The interlayer constraining layer 6 need not be formed on all of the ceramic green sheets 21 that provide each of the plurality of ceramic layers 2 provided in the laminate 3 shown in FIG. For example, the interlayer constraining layer 6 is not formed on the uppermost ceramic layer 2 among the plurality of ceramic layers 2 shown in FIG. 6 is not formed. Although not shown, there may be a ceramic green sheet 21 positioned in the middle where the interlayer constraining layer 6 is not formed.

  In the above description, the interlayer constraining layer 6 is formed on the ceramic green sheet 21 after the ceramic green sheet 21 is prepared. First, the interlayer constraining layer 6 is prepared and formed thereon. The ceramic green sheet 21 may be formed.

  Next, as shown in FIG. 3 (3), a through hole 22 is formed using, for example, a drilling machine or a laser so as to penetrate the ceramic green sheet 21 and the interlayer constraining layer 6. The through hole 22 is for providing the via hole conductor 5 shown in FIG.

  Next, as shown in FIG. 3 (4), the through-hole 22 is filled with a conductive paste, thereby forming the via-hole conductor 5. In order to apply the conductive paste into the through hole 22, for example, a screen printing method is applied.

  As the above-mentioned conductive paste, for example, a binder, a solvent, and a conductive powder containing at least one metal selected from Ag, Au, Cu, Ni, Ag—Pd, and Ag—Pt as main components. A mixture obtained by adding a predetermined amount of an organic vehicle and stirring and kneading with a stirring crusher and a three-roll mill can be used.

  The central particle size and particle shape of the conductive powder are not particularly limited, but those having a central particle size of 0.3 to 10 μm and having no coarse powder or extremely agglomerated powder are desirable.

  Further, the binder and the solvent constituting the organic vehicle are not particularly limited, but as the binder, for example, ethyl cellulose, acrylic resin, polyvinyl butyral or methacrylic resin can be used, and as the solvent, for example, terpineol, butyl Carbitol, butyl carbitol acetate or alcohols can be used.

Moreover, you may add a dispersing agent, a plasticizer, and an activator to an electrically conductive paste as needed. Furthermore, in order to match the shrinkage behavior with ceramic, glass frit, metal oxides such as Cu ₂ O, ceramic powder and / or resin powder may be added to the conductive paste in the range of 70% by weight or less. Good. The viscosity of the conductive paste is preferably 50 to 700 Pa · s ⁻¹ in consideration of printability.

Next, toward the ceramic green sheet 21 on which the interlayer constrained layer 6 shown in FIG. 3 (4) is formed, the metal foil 11 held by the support 12 shown in FIG. The pressure is applied as shown in 1) and a pressure of about 100 kg / cm ² is applied, for example. When the support 12 is removed, the metal foil 11 is transferred onto the interlayer constraining layer 6 as shown in FIG. At this time, at least the surface of the metal foil 11 in contact with the interlayer constraining layer 6 is covered with Cu ₂ O. When the interlayer constraining layer 6 is not formed, the metal foil 11 is transferred onto the ceramic green sheet 21.

  When the resin adhesive that is burned off in the firing step is applied in advance to the surface of the metal foil 11 during the above-described transition, the adhesion of the metal foil 11 to the interlayer constraining layer 6 or the ceramic green sheet 21 can be increased.

  In order to obtain a state in which the metal foil 11 is formed on the interlayer constraining layer 6 or the ceramic green sheet 21, the ceramic green sheet 21 or the interlayer is directly applied without applying the transfer process from the support 12 as described above. The metal foil 11 may be formed on the constraining layer 6.

Next, a plurality of ceramic green sheets 21 including the ceramic green sheets 21 holding the metal foil 11 as shown in FIG. 4 (2) are laminated as shown in FIG. 4 (3), and then, for example, at a temperature of 80 ° C. And the raw laminated body 23 is obtained by pressing in the lamination direction on the conditions of a pressure of 200 kg / cm < ² >.

  Next, the raw laminate 23 is baked in a reducing atmosphere in a reducing atmosphere, for example, under conditions of a temperature of 900 ° C. and 1 hour, whereby the laminate 3 after sintering shown in FIG. Is obtained. In the laminate 3, the ceramic layer 2 is derived from the ceramic green sheet 21, and the conductor wiring layer 4 is derived from the metal foil 11.

In the firing step for obtaining such a laminate 3, the surface of the metal foil 11 constituting the conductor wiring layer 4 is covered with Cu ₂ O as described above. An anchor structure is formed with respect to 21 to increase the adhesive force at the interface between the conductor wiring layer 4 and the ceramic layer 2. Suppresses peeling.

  In this embodiment, an interlayer constrained layer 6 is formed on the raw laminate 23. Since the inorganic material powder for shrinkage suppression such as alumina powder contained in the interlayer constrained layer 6 is not substantially sintered in the firing step, the interlayer constrained layer 6 is not substantially contracted. Therefore, the shrinkage suppressing action by the interlayer constraining layer 6 is exerted on the ceramic green sheet 21, and the ceramic green sheet 21 is suppressed from shrinking in the main surface direction in the firing step. As a result, the stress resulting from the difference in shrinkage behavior at the interface between the interlayer constrained layer 6 and the ceramic layer 2 is suppressed. This also makes it possible to secure a high adhesive strength at the interface between the conductor wiring layer 4 and the ceramic layer 2. Moreover, the dimensional accuracy of the laminated body 3 after sintering can be increased, and therefore, the density of the wiring provided by the conductor wiring layer 4 and the via-hole conductor 5 can be achieved with high reliability.

  When the raw laminate 23 shown in FIG. 4 (3) is compared with the laminate 3 shown in FIG. 1, the conductor wiring layer 4 formed on the lower surface of the laminate 3 is shown in FIG. 4 (3). Is not shown. The conductor wiring layer 4 on the lower surface may be previously formed on the lowermost ceramic green sheet 21 before the lamination step for obtaining the raw laminate 23, or the raw laminate 23 After obtaining the above, the conductor wiring layer 4 may be formed on the lower surface thereof. Further, the conductor wiring layer 4 on the lower surface side is not formed of the metal foil 11 but may be formed of a conductive paste and simultaneously baked in the firing step of the raw laminate 23. Further, the conductive wiring layer 4 on the lower surface side may be formed by applying a conductive paste to the lower surface of the sintered laminate 3 and baking it.

  Next, as shown in FIG. 1, the chip-like electronic component 7 is mounted on the upper surface of the laminated body 3 after sintering, and is connected to the conductor wiring layer 4 on the upper surface via the solder bumps 8. The multilayer ceramic substrate 1 is completed.

  While the present invention has been described with reference to the illustrated embodiments, various other modifications are possible within the scope of the present invention.

  For example, in the above-described embodiment, the metal foil 11 used for forming the conductor wiring layer 4 may be replaced with a metal wire.

  Further, in the laminate 3 provided in the multilayer ceramic substrate 1, not all of the conductor wiring layer 4 is composed of the metal foil 11 or the metal wire, but a conductor wiring layer formed of a conductive paste is partly formed. It may be provided.

  In addition, the above-described embodiment is directed to a multilayer ceramic substrate used for, for example, an LC filter, a multichip module, a chip scale package, and the like. However, the present invention includes a plurality of laminated ceramic layers. As long as the multilayer body and the conductor wiring layer formed on the ceramic layer are provided, the present invention can also be applied to other multilayer ceramic electronic components such as a multilayer capacitor and a multilayer inductor.

  Next, experimental examples carried out to confirm the effects of the present invention will be described.

(Experimental example)
Mixing powders of barium oxide, silicon oxide, alumina, calcium oxide and boron oxide with a binder made of polyvinyl butyral, a plasticizer made of di-n-butyl phthalate, and a solvent made of toluene and isopropylene alcohol. A slurry was prepared, and this slurry was formed into a sheet shape on an organic film by a doctor blade method and dried to obtain a ceramic green sheet having a thickness of 100 μm.

  Next, a borosilicate glass powder having a softening point of 780 ° C. and a particle size of 1.5 μm is added to 65% by volume of alumina powder so as to be 35% by volume, and a binder made of polyvinyl butyral and di-n-butyl phthalate are added. A slurry obtained by adding a plasticizer consisting of the above and a solvent consisting of toluene and isopropylene alcohol and mixing them was applied onto the ceramic green sheet described above to form an interlayer constrained layer on the ceramic green sheet. .

  Next, the metal foil which consists of conductor materials as shown in Table 1 and Table 2 was prepared. Here, for Cu foil, Ag foil, Al foil and Ni foil according to samples 1 to 20 and 30 to 47, those having a thickness of 18 μm are prepared, and for Au foils according to samples 21 to 29, having a thickness of 3 μm Prepared.

For each of the Cu foil, Ag foil, Al foil, Ni foil, and Au foil prepared in this way, as shown in Tables 1 and 2, samples that were not subjected to surface coating (Samples 1, 12, 21, and 30) And 39), as a surface coating, a film made of Cr, Mo, Cr ₂ O ₃ , Mo ₂ O ₃ , Al ₂ O ₃ , Ti, TiO ₂ or NiO having a thickness of about 0.5 μm is formed by electroless plating. Each sample (Samples 4 to 11, 13 to 20, 22 to 29, 31 to 38, and 40 to 47) was formed. Regarding the Cu foil, a sample (sample 2) in which Cu ₂ O was formed on the surface by heat treatment at a temperature of 300 ° C. for 30 minutes in an oven introduced with air at a flow rate of about 5 liters / minute, and a temperature of 600 ° C. And a sample (sample 3) having CuO formed on the surface was prepared by heat treatment for 30 minutes.

  Next, the metal foil according to each of the above-described samples is pasted on the acrylic film, and further a photosensitive film having a thickness of 20 μm is pasted thereon, and an exposure pattern is formed to give a desired circuit pattern. After being masked by the glass original plate and subjected to exposure treatment, development processing was performed so as to give a desired pattern to the photosensitive film.

  Next, using the photosensitive film patterned as described above as a resist, each metal foil was etched at an etching rate of 5 to 30 μm / min to give a desired pattern to the metal foil. Here, as an etchant, an ammonium persulfate aqueous solution is used for Cu foil, nitric acid is used for Ag foil, potassium cyanide is used for Au foil, and phosphoric acid and acetic acid are used for Al foil. A mixed solution with nitric acid was used, and hydrochloric acid was used for the Ni foil.

  Next, the resist made of a photosensitive film was peeled off. As a result, a conductor wiring layer made of a metal foil having a plane size of 0.1 mm × 20 mm was obtained.

Next, the conductor wiring layer made of each metal foil patterned on the film as described above was transferred to the ceramic green sheet on which the interlayer constraining layer was formed by applying a pressure of 100 kg / cm ² . .

Next, nine ceramic green sheets on which neither a conductor wiring layer nor an interlayer constraining layer is formed are overlaid. On the fifth sheet, the conductor wiring layer obtained as described above is held and an interlayer constraining layer is formed. The formed ceramic green sheet was inserted and pressed in the laminating direction under conditions of a temperature of 80 ° C. and a pressure of 200 kg / cm ² to obtain a raw laminate. In this raw laminated body, each end of the conductor wiring layer was exposed to the opposite side surfaces.

  Next, a predetermined amount of a binder made of polyvinyl butyral and a solvent made of terpineol are added to a conductive powder containing Cu as a main component and having a center particle size of 0.8 μm, and the mixture is stirred with a stirring crusher and a three roll mill. The conductive paste obtained by kneading was applied to the side surface of the raw laminate by a known printing method so as to be in electrical contact with the conductor wiring layer in the raw laminate.

  Next, the raw laminate described above was treated to remove the binder, and then fired in a reducing atmosphere at a temperature of 900 ° C. for 1 hour to obtain a multilayer ceramic substrate serving as an evaluation sample.

  Next, the substrate deformation amount of the multilayer ceramic substrate as the evaluation sample was measured with a stylus type surface roughness meter. With respect to the amount of substrate deformation, a case of 30 μm or more is evaluated as defective.

  Further, the multi-layer ceramic substrate as an evaluation sample was subjected to an electrical continuity test by a two-terminal method using a digital multimeter, and the presence or absence of occurrence of disconnection was evaluated by disconnecting 100Ω or more.

  Further, the multilayer ceramic substrate as an evaluation sample was cut perpendicularly to the plane of the conductor wiring layer so as to cross the conductor wiring layer, and the vicinity of the interface between the conductor wiring layer and the ceramic portion was measured with a metal microscope. Observation was performed at a magnification of 1000 times, and when a void having a diameter of 5 μm or more was observed, delamination was generated, and thereby the presence or absence of delamination was evaluated.

  Tables 1 and 2 below show the evaluation results described above.

In Tables 1 and 2, the sample numbers marked with * are samples outside the scope of the present invention in that the metal foil was not surface-coated. On the other hand, Sample 2 is a sample within the scope of the present invention. Samples 4 to 11, 13 to 20, 22 to 29, 31 to 38, and 40 to 47 other than these used materials other than Cu as the conductor material, or materials other than Cu ₂ O as the surface coating material. This is a sample as a reference example outside the scope of the present invention.

  Referring to Table 1 and Table 2, the metal foil for forming the conductor wiring layer was not subjected to surface coating, such as Samples 1, 12, 21, 30 and 39 with * added to the sample number. Delamination occurred.

  Further, as in Sample 3, in which a conductor wiring layer made of Cu foil was formed and the Cu foil was surface-coated with CuO, delamination did not occur, but the shrinkage due to the reduction reaction was small. Since it was large, the amount of deformation of the substrate was large, and disconnection occurred.

  On the other hand, according to Sample 2 within the scope of the present invention, the amount of substrate deformation is small as in Samples 4-11, 13-20, 22-29, 31-38, and 40-47 as reference examples. No disconnection occurred and no delamination occurred.

1 is a cross-sectional view schematically showing a multilayer ceramic substrate 1 obtained by applying an embodiment of the present invention. FIG. 3 is a cross-sectional view sequentially showing steps for obtaining a conductor wiring layer 4 provided in the multilayer ceramic substrate 1 shown in FIG. 1. FIG. 2 is a cross-sectional view sequentially illustrating steps applied to a ceramic green sheet 21 in order to obtain a ceramic layer 2, a via-hole conductor 5 and an interlayer constraining layer 6 provided in the multilayer ceramic substrate 1 shown in FIG. 1. A laminated body 3 provided in the multilayer ceramic substrate 1 shown in FIG. 1 using the metal foil 11 shown in FIG. 2 (3) and the ceramic green sheet 21 on which the interlayer constrained layer 6 shown in FIG. 3 (4) is formed. It is sectional drawing which shows the process for obtaining the raw laminated body 23 for for one by one.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multilayer ceramic substrate 2 Ceramic layer 3 Laminated body 4 Conductor wiring layer 6 Interlayer constrained layer 11 Metal foil 21 Ceramic green sheet 23 Raw laminated body

Claims (2)

A laminate comprising a plurality of laminated ceramic layers, and a conductor wiring layer formed on the ceramic layer, the ceramic layer comprising a low-temperature sintered ceramic material from which glass is produced upon firing; The laminate is formed of an inorganic material powder for shrinkage suppression that is positioned along a specific interface between the plurality of laminated ceramic layers and that is not sintered at a sintering temperature of the low-temperature sintered ceramic material included in the ceramic layer. A method for producing a multilayer ceramic electronic component , further comprising an interlayer constraining layer comprising :
Preparing a metal foil or metal wire containing Cu, which will be the conductor wiring layer;
Covering at least one surface of the surface of the metal foil or metal wire with Cu ₂ O;
Holding the conductor wiring layer with a ceramic green sheet to be the ceramic layer;
Laminating a plurality of the ceramic green sheets holding the conductor wiring layer;
Firing a green laminate composed of a plurality of the laminated ceramic green sheets ,
The step of holding the conductor wiring layer with the ceramic green sheet to be the ceramic layer includes the step of forming the interlayer constraining layer on the specific ceramic green sheet, and the one side covered with the Cu ₂ O. Holding the conductor wiring layer by the ceramic green sheet formed with the interlayer constraining layer so as to be in contact with the interlayer constraining layer,
The step of laminating the plurality of ceramic green sheets holding the conductor wiring layer includes laminating the plurality of ceramic green sheets so that the interlayer constraining layer is positioned along an interface between the plurality of ceramic green sheets. Including the step of
Manufacturing method of multilayer ceramic electronic component. The multilayer ceramic electronic component according to claim 1, wherein the step of covering the metal foil or the metal wire with Cu ₂ O includes a step of heat-treating at least a part of the surface of the metal foil or the metal wire in an oxidizing atmosphere. Manufacturing method.

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